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Sultran passes 20th anniversary milestone

Summary

In February this year, the Canadian sulphur industry's logistics management company, Sultran Ltd, recorded the 20th anniversary of its operational debut. In Just two decades, the company has created a modern, integrated and reliable transportation and terminal system for West Canadian sulphur; and it has consolidated the cost effectiveness of these facilities via a continuous programme of capital investment, product diversification, and technology improvement. Today's smoothly running offshore export sulphur transportation programme is a far cry from the early days of the business, and a reminder of just how much has been achieved in a relatively short time.

Abstract

During the early stages of the sulphur industry'S development in Alberta, from 1957 onwards, the producers initially looked to sales outlets elsewhere in Canada and in the United States. But the centres of sulphur demand in both countries, Eastern Canada and the Florida phosphate industry, were well covered by competing supply sources notably in the form of by-product sulphuric acid from the non-ferrous metal smelters in Ontario and liquid sulphur from the Frasch mines in Texas and Louisiana. And compounding the sales difficulties were the lengthy rail hauls of over 3,000km to these markets plus the low market prices for sulphur in the late-1950s.

Copper projects boost sulphuric acid industry in Chile

Summary

The growth of copper production in Chile, plus the improved environmental controls at the industry's smelters, are combining to lift the country's output of by-product sulphuric acid, for which there is an active market in the expanding number of ore leaching operations. Recent developments in the sector are summarised by Martin Horseman.

Abstract

Chile is the world's fifth largest source of smelter-based sulphuric acid, and in 1996 the annual level of production exceeded 2 million tonnes H2S04 for the first time. Virtually all of this production stems from the exploitation of SO2-containing smelter off-gases in the copper industry, but there is an additional supply of some 35,000 tly from a molybdenum smelter situated near Santiago.

longtime mainstay of the national 30 economy, and the country has been the world's largest producer of copper since surpassing the level of US production in the early-1980s. Mine output of copper exceeded 3.0 million tonnes (Cu content) in 1996, and the production rate has virtually doubled since 1990, when output amounted to some 1.6 million tonnes.

The expansion of copper mine production has been accompanied by the substantial growth of refinery operations, with output having accelerated in recent years to reach some 1.75 million tonnes in 1996, compared to about 1.2 million tonnes in 1990

Much of the uplift in refinery output has been occasioned by the introduction of new solvent extraction/ electrowinning (SXJEW) plants associated with copper ore leaching operations. The advance of hydrometallurgy in the Chilean copper industry has been a particular feature of the mid-1990s, and it has propelled sulphuric acid demand to new heights. Further ore leaching and SXlEW projects scheduled for the remainder of the decade will serve to continue the surge in acid consumption.

A record crowd

Summary

This year's AIChE meeting at Clearwater included a session on sulphuric acid operations and technology for the first time. No surprise, then, that over 370 people registered.

Abstract

"The Clearwater" really came of age this year. The 21st Annual Memorial Weekend Conference of the AIChE Central Florida Section on Phosphate and Sulfuric Acid Technology was held at the Sheraton Sand Key Resort, Clearwater, Florida, from 23 to 26 May. Originally devised as a half-day local meeting for members of the Central Florida Section, which predominantly serves the Florida phosphate industry, on their way to lie on the beach with their families over the long Memorial Day weekend, this conference has been growing in recent years, both in its coverage and in its attendance. In addition to the original single half-day session on the Saturday morning, which is traditionally concerned with phosphate topics, a "workshop" session on a particular aspect of phosphates production is now held on the Friday afternoon (this year it was on phosphoric acid filters), and this year, for the first time, a new session on sulphuric acid topics was held in parallel with the general phosphate session on the Saturday morning.

250 years of vitriol 3: Hardware challenges

Summary

In the concluding part of our historical survey of sulphuric acid technology, we trace the development of materials of construction and its effect on some of the more problematic items of process equipment.

Abstract

The previous instalments of this article followed the development of the lead chamber sulphuric acid process and variants of itl and the advent and further development of the contact process, which is the principle of virtually all sulphuric acid plants today.

The pace of development of manufacturing technology for a given product is largely governed by the rate of improvement in the technology of the key items of equipment and, above all, of the materials of which they are made. This final instalment examines the relationship between the development of materials of construction and that of the most critical items in the process train. For reasons of space, it is restricted to the acid plant proper and does not comprehend the means for producing the sulphur dioxide feed gas.

Addressing the problem of spent acid

Summary

Spent acid regeneration provides the most environmentally acceptable means of dealing with the enormous quantities of spent sulphuric acid produced worldwide by a myriad of industrial chemical processes. In this article Lisa Connock reports on the technology and services offered by leading companies in this field.

Abstract

Sulphuric acid is used in many industrial chemical processes. In the vast majority of these processes it acts as a reaction medium and does not form part of the final product. Because of this, enormous volumes of dilute and contaminated acid (spent sulphuric acid) are produced as a waste product. Dealing with this spent acid represents an environmental problem that has become increasingly complex and costly as production capacities have increased and environmental regulations have become more stringent.

The bulk of the spent acid is generated by the organic chemical and petrochemical industries. Typical processes resulting in spent sulphuric acid include alkylation (used to make unleaded gasoline), sulphonation (used to make ion exchange resins, organic dyes, surfactants for detergents and pharmaceutical intermediates), nitration (used to make toluene diisocyanate, agrochemical intermediates and explosives for civilian and military use), and gas drying and purification (used to make methyl chloride, chlorine, monomer vinyl acetate and organic peroxides). The concentration and chemical composition of spent acid varies widely according to the process. The acids may be very dilute or fairly concentrated with high or low levels of organic and inorganic impurities. Large volumes of uniform spent acid arise only in the course of plastics production (e.g. methyl methacrylate and caprolactam). Typical data showing the composition of different types of spent acid are shown in Table 1.

In the inorganic chemical industry, the titanium dioxide (TiOz) pigment industry generates large volumes of spent acid of relatively uniform quality containing approximately 20-25% H2S04 and 7-15% metal sulphates. Titanium dioxide production by the sulphate process produces around seven tonnes of spent sulphuric acid p~r tonne of titanium dioxide. Other sources of spent acid is obtained from pickling operations in the metallurgical industry and from the gas cleaning section of metallurgical acid plants.

In the past, typical methods for disposal or recycling of spent sulphuric acids included: neutralizing with ·lime, ocean or river dumping, and reconcentrating/blending with oleum.

Neutralization of spent acid is undesirable due to the resulting large volumes of impure gypsum which must be landfilled. The cost of landfilling has increased significantly in recent years and in some cases the gypsum · may contain toxic compounds which make it environmentally unacceptable for landfill. Stricter environmental regulations have virtually eliminated the practice of ocean or river dumping; and the reconcentration of weak acids by blending with oleum is only suitable for small acid volumes involving high HZS04 concentrations and with specific impurity content.

The only method available for processing the spent acid to obtain a product of original quality while complying with environmental regulations is therefore spent acid regeneration, i.e. the recovery, reconcentration and recycle of spent sulphuric acid.

Spent acid regeneration technology and processing is available from a variety of companies. In the remainder of this article we report on what is available from some of the key players.